A power supply system having an energy conversion unit converting energy, other than electricity, into electric power, and a capacitor has conventionally been known. There is a solar cell system having a solar cell and a capacitor, which are connected in parallel, as one example of the power supply system described above.
However, when the solar cell and the capacitor are connected in parallel, electric power from the one having high output voltage is fed to a load, regardless of a power supplying capability. Specifically, in the background art, a power supply source (solar cell, capacitor) to the load cannot explicitly be selected (in other words, the power supply source cannot appropriately be selected). Therefore, the load connected to the power supply system is limited to the one whose maximum consumption power is not more than the maximum generated power of the solar cell.